The BRMP has a keen interest in cytokine and AIDS research, therefore, the LBP has initiated a study on the identification of sequence-specific DNA-binding proteins regulating the transcription of IL-2/IL-2R promoters and HIV-LTR. Using a Southwestern screening technique, several cDNA clones encoding the proteins that bind to different DNA elements have been isolated. One group of the mouse cDNA clones encoding the proteins that bind to the positive regulatory element of the IL-2R promotor sequence -261 to -244. The deduced amino acid sequence contains a zinc-finger DNA binding motif (C-X3-C-C-Xl2-C-X6-C), followed immediately by a short leucine zipper structure (L-X6-L-X6-L), characteristic of DNA-binding proteins. A second mouse cDNA clone encodes the protein that binds to the sequence -94 to -64 of the IL-2 promoter. It has been reported that this DNA element is involved in the negative regulation of IL-2 gene expression in resting T-cells. Functional roles of these DNA-binding proteins in determining T-cell specific gene expression of IL-2/IL-2R will be investigated. Both the IL-2R alpha gene and the HIV-LTR are activated by various T cell mitogens. Therefore, we have extended our IL-2/IL-2R studies to the HIV system. A 12 bp sequence present in the regulatory region of the IL-2R alpha gene (sequence -267 to -256) is remarkably similar to the HIV enhancer element (HIV-DR; DR: direct repeats). Using HIV-1 enhancer oligonucleotides (sequence -137 to -17) as the probe, we have isolated a human cDNA clone by Southwestern screening technique. Characterization of the cDNA clone is in progress.